Metal recovery process

ABSTRACT

METALLIC COMPONENTS ARE RECOVERED FROM A HYDROCARBON MIXTURE BY (1) FORMING THE SULFIDES OF THE METALS, (2) CONVERTING THE SULFIDES TO METAL CARBONYLS AND (3) SEPARATING THE CARBONYLS FROM THE HYDROCARBON MIXTURE. ESPECIALLY ADAPTABLE FOR THE RECOVERY OF A COLLOIDAL METAL CATALYST FROM THE REACTION PRODUCT EFFLUENT OF A SLURRY PROCESS FOR THE CONVERSION OF HEAVY HYDROCARBONACEOUS CHARGE STOCKS. THE EFFLUENT, IN WHICH THE METAL EXISTS IN THE SULFIDE FORM, IS TREATED WITH CARBON MONOXIDE WHICH PRODUCES THE CARBONYL. THE METAL CARBONYL IS CAPABLE OF SUBSEQUENT USE AS THE PRECURSOR OF THE COLLOIDAL METAL CATALYST.

United States Patent O 3,720,603 METAL RECOVERY PROCESS William K. T. Gleim, Island Lake, [1]., assignor to Universal Oil Products Company, Des Plaines, Ill. No Drawing. Filed Feb. 5, 1971, Ser. No. 113,109 Int. Cl. C10g 17/00 US. Cl. 208-251 R Claims ABSTRACT OF THE DISCLOSURE APPLICABILITY OF INVENTION Within its broad scope, the present invention is adaptable to a process for the recovery of metal values from hydrocarbons. More specifically, my invention involves the recovery of a colloidal metal catalyst which has been utilized in a slurry-type process for the conversion of hydrocarbons. My invention is further applicable to the recovery of metals which exist as metallic contaminants in crude petroleum stocks and the heavier fractions derived therefrom.

Crude petroleum oils, including shale oil, tar sands oil, coal oil extract, etc., and various heavy fractions derived therefrom, such as crude residuum, vacuum tower bottoms, atmospheric tower bottoms, etc., are considered contaminated through the inclusion of excessive quantities of metallic impurities principally comprising nickel and vanadium, although other metals including copper, iron and zinc are often present. In addition, these heavier petroleum fractions are known to contain exceedingly large quantities of sulfurous and nitrogenous compounds. The metal impurities exist primarily as organo-metallic complexes which are linked with sulfur in the non-distillable (greater than about 1050 F.) fraction, and become concentrated in the residual portion when the charge stock is subjected to a conversion process.

It is generally conceded that the presence of the metalcontaining non-distillables precludes fixed-bed catalytic processing, whether for hydrogenation, hydrocracking, or both, in view of the rapid catalyst activity decline rate stemming from coke and metal deposition. Acknowledgment is also made of the fact that the ever-increasing need for voluminous quantities of lower boiling hydrocarbonse.g. naphtha, kerosene, fuel oil, etc.virtually demands conversion of the heavier material to the grestest possible extent, even to the conversion of the so-called bottom of the barrel. In order to achieve this end result, while providing a commercially acceptable scheme from an economic standpoint, fixed-bed catalytic conversion is necessarily a part of the involved technique.

One solution to the problem arising from the presence of the metallic contaminants involves the removal thereof prior to fixed-bed processing. Utilization is often made 70 stock; this scheme is detailed in United States Pat. No.

3,720,603 Patented Mar. 13, 1973 Since such cleasphalting and metal-recovery processes result in the loss of non-metallic resins, as distinguished from metal-containing asphaltics, which are not then subsequently converted, recent technology has been developed in the area of catalytic slurry-type processing. The latter process is effected by admixing a finely-divided catalytic agent with the feed stock and reacting the mixture in a hydrogen atmosphere at elevated pressure and temperature. Considering the degree of conversion to lower-boiling hydrocarbon products, as well as the degree of desulfurization and denitrification, such a slurry-process appears to offer the most economical solution to the problem as above set forth.

Slurry processing utilizes a finely-divided metal, or the oxide or sulfide thereof, with the sulfide being preferred. In many instances, the catalytic metal will be in the form of a heat-decomposable complex which becomes converted to the sulfide form. The catalytic metal sulfide, as well as sulfides of the metal contaminants are recovered as an asphaltic sludge following separation of the product efliuent. Current methods for the recovery of the metal values, especially for re-use as the catalytic component, involve arduous techniques much the same as that disclosed in the foregoing mentioned Pat. No. 3,522,001.

My invention is intended to be utilized for the recovery of (1) the colloidal metal catalyst used in slurry processing and/or (2) the metal values originally present in the crude stock as contaminating influences.

OBJECTS AND EMBODIMENTS A principal object of my invention is to recover metal values from hydrocarbon mixtures. A corollary object resides in the intent to recover the colloidal metal catalyst employed for the conversion of hydrocarbons in a slurrytype process.

Another object is to recover metal values from metalcontaminated crude stocks in a form which facilitates their use as precursors of colloidal metal catalysts.

In one embodiment, therefore, my invention provides a process for the recovery of a metal from a hydrocarbon mixture which comprises the steps of: (a) forming the sulfide of said metal; (b) converting said metal sulfide to a metal carbonyl; and (c) separating said carbonyl from said hydrocarbon mixture.

A more specific embodiment of my invention involves a method for the removal of a colloidal metal catalyst from a reaction product efiiuent which comprises the steps of: (a) removing normally gaseous components from said effluent; (b) admixing said efiiuent with carbon monoxide at a pressure from 500 to about 3,000 p.s.i.g. and a temperature of 50 C. to C.; and separating said effluent at a reduced pressure to provide a substantially metal-free product and to recover said colloidal metal as the carbonyl thereof.

Other objects and embodiments will become evident from the following description of my invention.

SUMMARY OF INVENTION In accordance with the method encompassed by the present invention, metal values are recovered from hydrocarbon mixtures as metal carbonyls. The carbonyls are formed by admixing the hydrocarbon with carbon monoxide under a pressure of 500 to about 3,000 p.s.i.g. and a temperature less than about 150 C. Since the metal carbonyls decompose at temperatures greater than C., a preferred temperature is in the range of 50 C. to about 150 C. Carbon monoxide reacts with metal sulfides, thereby forming the carbonyl which is readily recovered from the hydrocarbon by a relatively simple fractionation technique. Therefore, prior to contacting the carbon monoxide and metal-containing hydrocarbon, the metal values should exist as metal sulfides.

When the hydrocarbon mixture is the reaction product effiuent from a catalytic slurry process, the metal values are already in the form of sulfides as a result of the hydrogenative cracking reactions which have converted sulfurous compounds into hydrogen sulfide and hydrocarbons. Recovery of metals from a virgin charge stock can be effected by treating the hydrocarbon mixture with a mixture of hydrogen sulfide and hydrogen at elevated temperature and pressure. However, in view of the fact that both hydrogenative cracking and desulfurization take place, the resulting hydrocarbon mixture can properly be categorized as a reaction product effluent. The metals recovered therefrom will principally be nickel and iron, both of which are suitable, in the carbonyl form, for use with fresh charge stock as catalyst precursors.

The utilization of metal carbonyls, such as those from Group VI-B and the iron group, as catalyst precursors for a slurry-type operation, is set forth in detail in U.S. Pat. No. 3,173,860 (Cl. 208264). Included are the carbonyls of molybdenum, iron, tungsten, nickel and cobalt. These compounds, as well as the carbonyl of vanadium decompose at temperatures above 160 C. to 200 C. to form a colloidal metal dispersion which chemically reacts with the organically-bound sulfur to form a metal sulfide, and also catalyzes hydrocracking and hydrogenation of portions of the charge stock. The total product efiluent is subjected to a series of separation techniques to provide a hydrogen-rich recycle gas and to recover normally liquid hydrocarbons. The metal sulfides resulting from both the colloidal metal catalyst and the virgin metals of the feed stock are separately recovered, along with unconverted asphaltics, in the form of a heavy hydrocarbonaceous sludge from which the metals are recovered.

In accordance with my invention, the product effluent is initially introduced into a hot separator at substantially the same pressure and temperature, as it emanates from the reaction chamber, to provide a vaporous phase and a normally liquid hydrocarbon phase containing the metal sulfides. The former is then introduced into a cold separator, again at substantially the same pressure, but at a lower temperature from 60 F. to 140 F. A second, hydrogen-rich vaporous phase is recovered for ultimate use as recycle to the reaction chamber. Condensed hydrocarbons are generally sent to fractionation facilities.

The metal sulfide-containing phase from the hot separator is usually subjected to vacuum distillation in present-day processes. However, in accordance with my invention, this phase is treated with carbon monoxide at a temperature of 50 C. to 150 C. and substantially the same pressure to convert the metal sulfides to the metal carbonyls. Such treatment is conveniently conducted in a second reaction chamber utilizing a circulating stream of carbon monoxide for a time sufiicient to convert the various metal sulfides to the carbonyls. The effluent is then subjected to fractionation at a pressure in the range of atmospheric to 150 p.s.i.g. for separate recovery of the carbonyls. Where desired, the liquid efiluent from the cold separator may be recombined with the liquid phase from the hot separator prior to the carbon monoxide treatment.

PREFERRED EMBODIMENT DESCRIPTION A vacuum column bottoms derived from a Middle-East crude oil, and containing about ppm. by weight of vanadium and nickel, is admixed with iron pentacarbonyl in an amount of about 10.0% by weight, calculated as elemental iron, and, following decomposition at a temperature of about 200 C., placed in an autoclave under an imposed hydrogen pressure of 200 atmospheres and at a temperature of 400 C. After a period of eight hours, the autoclave is cooled and depressed to remove unreacted hydrogen and other normally gaseous components. The autoclave is then repressured to 200 atmospheres with carbon monoxide, the temperature being about 150 C. After an other period of about eight hours, the autoclave is again cooled and depressured. The contents are then fractionated at a pressure of about p.s.i.g. and a fractionator bottoms temperature of about C.

The metal carbonyl-containing fraction is recovered and analyzed; the results indicate about 93.5% recovery of the catalytic iron and about 89.2% recovery of the original nickel.

The foregoing indicates the method of effecting the present invention and the benefits to be afforded through the utilization thereof.

I claim as my invention:

1. A process for the removal of finely divided metal sulfied from a hydrocarbon liquid containing the same which comprises commingling carbon monoxide with said liquid at a pressure of from about 500 to about 3000 p.s.i.g. and a temperature of from about 50 C. to about 150 C. and reacting the carbon monoxide with said sulfide to form metal carbonyl, and fractionating the resultant reaction mixture to separate said metal carbonyl and form a substantially metal-free hydrocarbon product.

2. The process of claim 1 further characterized in that said reaction mixture is fractionated at a pressure of from atmospheric to about 150 p.s.i.g.

3. The process of claim 1 further characterized in that the metal of said sulfide is selected from the group consisting of iron, nickel and cobalt.

4. The process of claim 1 further characterized in that said hydrocarbon liquid is the reaction product effluent of a hydrocarbon conversion process employing a colloidal metal catalyst.

5. The process of claim 1 further characterized in that said hydrocarbon liquid is a metal-contaminated crude petroleum fraction in which the metal contaminant has been converted to metal sulfide.

References Cited UNITED STATES PATENTS 3,151,088 9/1964 Sanford et al. 2524l6 3,595,965 7/1971 Franz et a1. 23203 C 3,598,528 8/1971 Franz et al. 23209.9 2,985,504 5/1961 Orchin 23-14 3,173,860 3/1965 Gatsis 208264 DELBERT E. GANTZ, Primary Examiner J. M. NELSON, Assistant Examiner U.S. Cl. X.R. 208264; 423-417 

